A metal detector for buried and corroded pipeline is provided, comprising: a transmitting coil configured to transmit a detection signal to a pipeline; a frequency selection unit electrically connected to the transmitting coil for regulating a frequency of the detection signal; two receiving coils respectively and symmetrically disposed at two opposite sides of the transmitting coil for respectively receiving a reflected signal returned from the pipeline; an analog-digital conversion unit respectively and electrically connected to the two receiving coils for converting the reflected signal into a digital signal; and a control unit electrically connected to the analog-digital conversion unit. In the present disclosure, by comparing intensities of the reflected signals received by the two receiving coils, it can be efficiently and accurately determined whether corrosion has occurred to the pipeline.

A triangular-voltage generator has an input terminal that receives a power supply voltage and an output terminal that supplies a triangular-wave voltage having a repetition period. An operational amplifier in an integrator configuration has a first input, a second input and an output coupled to the output terminal. The second input receives a reference voltage as a function of the power supply voltage. The first input is selectively and alternately connected to the input terminal during a first half-period of the repetition period and to a reference terminal during a second half-period of the repetition period.

An equalizer circuit and related power management circuit are provided. The power management circuit includes a voltage amplifier circuit configured to generate an envelope tracking (ET) voltage based on a differential target voltage and provide the ET voltage to a power amplifier circuit(s) via a signal path for amplifying a radio frequency signal(s). An equalizer circuit is provided in the power management circuit to equalize the differential target voltage prior to generating the ET voltage. Specifically, the equalizer circuit is configured to provide a transfer function including a second-order complex-zero term and a real-zero term for offsetting a transfer function of an inherent trace inductance of the signal path and an inherent impedance of the voltage amplifier circuit. By employing the second-order transfer function with the real-zero term, it is possible to reduce distortion in the ET voltage, especially when the RF signal(s) is modulated in a wide modulation bandwidth.

A triangular-voltage generator has an input terminal that receives a power supply voltage and an output terminal that supplies a triangular-wave voltage having a repetition period. An operational amplifier in an integrator configuration has a first input, a second input and an output coupled to the output terminal. The second input receives a reference voltage as a function of the power supply voltage. The first input is selectively and alternately connected to the input terminal during a first half-period of the repetition period and to a reference terminal during a second half-period of the repetition period.

A Doherty amplifier includes: an input port; a pre-amplification stage; and at least one output port. The Doherty amplifier further includes: a high-band amplification pathway; a low-band amplification pathway; the high-band amplification pathway (VA.sub.HB) and the low-band amplification pathway each having a main amplifier, an auxiliary amplifier, and an output impedance matching network. A common network is connected to the high-band amplification pathway and to the low-band amplification pathway, the common network having a switch configured to selectively activate the high-band amplification pathway or the low-band amplification pathway. An intermediate impedance matching network is distributed between the common network, the high-band amplification pathway and the low-band amplification pathway.

Provided is a differential amplifier comprising: a first differential amplification circuit that has a first input terminal, a second input terminal, a first output terminal and a second output terminal which respectively output a first output signal and a second output signal; an RC filter that filters the first output signal and the second output signal and outputs them; a second differential amplification circuit that has a third input terminal and a fourth input terminal to which the first output signal and the second output signal filtered by the RC filter are respectively input and a third output terminal which outputs a third output signal; and a third amplification circuit that has a fifth input terminal to which the third output signal is input and a fourth output terminal which outputs a fourth output signal according to the third output signal.

The present application discloses an amplifier, including: a positive-end PMOS; a negative-end PMOS; a positive-end NMOS, having a drain coupled to a drain of the positive-end PMOS and outputting a negative-end output signal; a negative-end NMOS, having a drain coupled to a drain of the negative-end PMOS and outputting a positive-end output signal; a first resistor, coupled between a gate of the negative-end NMOS and a negative-end input signal; a second resistor, coupled between a gate of the negative-end NMOS and the positive-end output signal; a third resistor, coupled between a gate of the negative-end PMOS and the negative-end input signal; and a fourth resistor, coupled between a gate of the negative-end PMOS and the positive-end output signal.

Wireless circuitry is provided that includes a circuit configured to output a radio-frequency signal and a power detector having an input configured to receive the radio-frequency signal. The power detector includes an input transistor and an attenuation circuit coupled to a gate terminal of the input transistor and having series and shunt capacitors of the same capacitor type. The series and shunt capacitors of the same capacitor type can be configured to automatically track process variations of one another for mitigating sensitivity to the process variations. The series and shunt capacitors can have adjustable capacitances that are tuned to adjust a linearity of the power detector.

An error amplifier including a differential pair circuit, a resistive device, a low voltage capacitor, and a protection device. The differential pair circuit is coupled between an upper supply node and a lower supply node with first and second intermediate nodes and is responsive to a difference between a reference voltage and a feedback voltage for driving a control voltage developed on the second intermediate node. The resistive device is coupled between the second intermediate node and a low voltage node, and the low voltage capacitor and the protection device are coupled between the low voltage node and the lower supply node. The protection device is dynamically controlled by the first intermediate node to prevent the low voltage node from exceeding a predetermined maximum level. The protection device may be a transistor having size parameters based on voltage characteristics of the first intermediate node during expected operating conditions.